JP6640684B2 - Evaluation method, correction method, program, and electron beam writing apparatus - Google Patents

Description

  The present invention relates to an evaluation method, a correction method, a program, and an electron beam drawing apparatus.

  In a lithography step of a recording medium such as a flash memory or a semiconductor element constituting a CPU (Central Processing Unit), an original pattern formed on a mask is transferred to a wafer serving as a substrate of the semiconductor element. The drawing of the original pattern on the mask is performed by, for example, an electron beam drawing apparatus.

  2. Description of the Related Art In recent years, from the viewpoint of improving throughput, a multi-beam type electron beam writing apparatus capable of writing a pattern using a plurality of electron beams has appeared. In this type of electron beam lithography apparatus, an electron beam emitted from one electron source passes through an aperture in which a plurality of openings are formed, whereby the electron beam is multiplexed. Therefore, the spot shape and the dose amount of each electron beam vary depending on the processing accuracy of the aperture.

  Therefore, various techniques for controlling the dose amount of an electron beam and the like have been proposed (for example, see Patent Document 1).

JP 2004-200549 A

  The dose of the electron beam can be controlled to some extent by adjusting the exposure time. However, considering that the number of electron beams used for writing will increase in the future, it is expected that it will be difficult to draw a pattern with high accuracy only by controlling the dose of the electron beam. Therefore, in order to draw a pattern with high accuracy, it is necessary to selectively use apertures with small variations in aperture shape and to first multiply electron beams with high accuracy.

  The present invention has been made under the above circumstances, and has as its object to multiply electron beams with high accuracy and to draw a pattern with high accuracy.

  In order to solve the above-described problem, an evaluation method according to the present embodiment is an evaluation method for evaluating the accuracy of an aperture in which a plurality of openings are formed, and includes a plurality of evaluation methods generated by passing an electron beam through the aperture. Drawing a first evaluation pattern based on the evaluation data by using the electron beam, dividing the aperture into a plurality of regions including a plurality of openings, and defining a plurality of divided regions; Drawing a second evaluation pattern different from the first evaluation pattern based on the evaluation data, using an electron beam passing through any one of the first divided regions; A step of comparing the pattern and a step of evaluating the accuracy of the aperture based on a comparison result of the first evaluation pattern and the second evaluation pattern.

  The first correction method according to the present embodiment is a correction method for correcting the dose of each of a plurality of electron beams passing through an aperture in which a plurality of openings are formed. And a step of defining a plurality of divided regions, and a plurality of electron beams generated by passing through the first divided region based on the evaluation data. Drawing a first evaluation pattern including: a step of obtaining a first correction value based on a difference in size of each mark included in the first evaluation pattern with respect to a preset reference pattern; Drawing a second evaluation pattern including a mark corresponding to each electron beam using a plurality of electron beams generated by passing through a second divided region different from the first divided region; The first evaluation pattern and the second evaluation pattern are compared, and a second correction value based on the difference between the mark of the first evaluation pattern and the mark of the second evaluation pattern corresponding to the mark of the first evaluation pattern is calculated. The step of obtaining and correcting the dose of the electron beam that has passed through the first divided area based on the first correction value, and has passed through the second divided area based on the sum of the first correction value and the second correction value. Correcting the dose of the electron beam.

  The second correction method according to the present embodiment is a correction method for correcting the dose of each of a plurality of electron beams passing through an aperture formed with a plurality of openings. Performing the method, obtaining a first correction value based on a difference between the sizes of the marks included in the second evaluation pattern with respect to the mark of the preset reference pattern, and based on the evaluation result of the evaluation method. Obtaining a second correction value based on the difference between the size of the mark included in the second evaluation pattern and the mark size of the first evaluation pattern; and passing through the first divided area based on the first correction value. Correcting the dose of the electron beam and correcting the dose of the electron beam that has passed through a divided region other than the first divided region based on the sum of the first correction value and the second correction value.

  The third correction method according to the present embodiment is configured such that, based on the evaluation data, a first pattern formed by shot the electron beam a first number of times, and the electron beam based on the evaluation data, A comparing step of comparing a second pattern formed by performing a second number of shots different from the first number of times, and a dose amount of the electron beam based on a comparison result between the first pattern and the second pattern. And a correcting step of correcting

  The program according to the present embodiment uses a plurality of electron beams generated when an electron beam passes through an aperture to evaluate data to a control device of an electron beam lithography apparatus having an aperture in which a plurality of openings are formed. Drawing a first evaluation pattern based on the divided aperture into a plurality of regions including a plurality of openings, defining a plurality of divided regions, passing through any one of the plurality of first divided regions A procedure for drawing a second evaluation pattern different from the first evaluation pattern based on the evaluation data, a procedure for comparing the first evaluation pattern with the second evaluation pattern, and a procedure for comparing the first evaluation pattern with the second evaluation pattern based on the evaluation data. A procedure for evaluating the accuracy of the aperture based on the comparison result of the two evaluation patterns is executed.

  An electron beam lithography apparatus according to the present embodiment is an electron beam lithography apparatus that draws a pattern on a sample, and a storage device that stores a program according to the embodiment, and a processing device that executes the program stored in the storage device And

  According to the present invention, since the accuracy of the aperture can be evaluated, the electron beam can be multiplexed using an aperture having high processing accuracy. Therefore, it is possible to draw a pattern with high accuracy.

FIG. 1 is a diagram illustrating a schematic configuration of an electron beam lithography apparatus according to an embodiment. It is a top view of an aperture. FIG. 3 is a perspective view of an electron gun, a lens, an aperture, and a blanking unit. It is a top view of a blanking unit. It is a perspective view which expands and shows a blanker. It is a block diagram of a control device. It is a flowchart of an evaluation pattern drawing process. It is a figure showing the SEM image of an evaluation pattern. FIG. 4 is a diagram for explaining an opening shape of an aperture. It is a figure showing the SEM image of an evaluation pattern. FIG. 4 is a diagram illustrating an area defined by an aperture. FIG. 9 is a diagram for explaining a procedure for drawing an evaluation pattern. FIG. 9 is a diagram for explaining a procedure for drawing an evaluation pattern. FIG. 9 is a diagram for explaining a procedure for drawing an evaluation pattern. FIG. 9 is a diagram for explaining a procedure for drawing an evaluation pattern. It is a figure showing the SEM image of an evaluation pattern. It is a figure showing the SEM image of an evaluation pattern. It is a figure showing the SEM image of an evaluation pattern. It is a figure showing the SEM image of an evaluation pattern. It is a flowchart of an evaluation process. It is a figure showing a difference picture. FIG. 6 is a diagram illustrating an area defined in a difference image. It is a figure which shows notionally the evaluation using a difference image. It is a flowchart of a correction process. It is a top view of an aperture. FIG. 4 is a diagram illustrating an area defined by an aperture. FIG. 3 is a diagram showing a mark drawn on a sample. It is a flowchart which shows a dose correction process. It is a figure showing the SEM image of an evaluation pattern. It is a figure showing the SEM image of an evaluation pattern. It is a figure showing the SEM image of an evaluation pattern. It is a figure showing the SEM image of an evaluation pattern. It is a figure showing a difference picture. It is a figure showing a difference picture. It is a figure showing a difference picture. It is a figure showing a difference picture.

<< 1st Embodiment >>
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the embodiment, an orthogonal coordinate system including an X axis, a Y axis, and a Z axis that are orthogonal to each other will be used as appropriate.

  FIG. 1 is a diagram showing a schematic configuration of an electron beam lithography apparatus 10 according to the present embodiment. The electron beam writing apparatus 10 is an apparatus that writes a pattern on a sample 120 such as a mask or a reticle coated with a resist material in a vacuum environment.

  As shown in FIG. 1, an electron beam lithography apparatus 10 includes an irradiation apparatus 20 that irradiates an electron beam EB to a sample 120, a stage 70 on which the sample 120 is mounted, a vacuum chamber 80 that houses the irradiation apparatus 20 and the stage 70. , A control system 100 for controlling the irradiation device 20 and the stage 70.

  The vacuum chamber 80 includes a writing chamber 80a that houses the stage 70, and a lens barrel 80b that houses the irradiation device 20.

The lighting chamber 80a is a rectangular parallelepiped hollow member, and has a circular opening formed on the upper surface. The lens barrel 80b is a cylindrical casing whose longitudinal direction is the Z-axis direction. The lens barrel 80b is made of, for example, stainless steel and is grounded. The lens barrel 80b is drawn into the interior of the lighting chamber 80a from an opening formed on the upper surface of the lighting chamber 80a. The inside of the lighting chamber 80a and the lens barrel 80b is maintained at, for example, a degree of vacuum of about 10 ⁻⁷ Pa.

  The irradiation device 20 includes an electron gun 30, three lenses 41, 42, 43, two apertures 51, 52, a blanking unit 61, and a deflector 62 disposed inside the lens barrel 80b.

  The electron gun 30 is disposed above the inside of the lens barrel 80b. The electron gun 30 is, for example, a hot cathode type electron gun. The electron gun 30 includes a cathode, a Wehnelt electrode provided to surround the cathode, an anode disposed below the cathode, and the like. The electron gun 30 emits the electron beam EB downward when a high voltage is applied.

  The lens 41 is an annular electromagnetic lens, and is disposed below the electron gun 30. The lens 41 shapes the electron beam EB that spreads downward and travels so as to be parallel to the vertical direction.

  The aperture 51 is a member for splitting the incident electron beam EB into a plurality of electron beams EBmn. FIG. 2 is a plan view of the aperture 51. FIG. As shown in FIG. 2, the aperture 51 is a square plate-shaped member. The aperture 51 is made of, for example, silicon or the like as a base material, and a plating film or a sputtered film of, for example, chromium is formed on the surface. In the aperture 51, 64 openings H are formed in a matrix of 8 rows and 8 columns with the row direction being the X-axis direction and the column direction being the Y-axis direction. The opening H is a square whose sides are parallel to the Y axis or the X axis, and the dimensions in the Y axis direction and the X axis direction are substantially equal between the openings H.

  In the present embodiment, 64 openings H are represented as Hmn using integers m and n of 1 to 8. The opening located in the first row on the + Y side is denoted as H1n. The openings located in the second to eighth rows are indicated as H2n to H8n. The opening located in the first column closest to the -X side is indicated as Hm1. The openings located in the second to eighth columns are indicated as Hm2 to Hm8.

  FIG. 3 is a perspective view of the electron gun 30, the lens 41, the aperture 51, and the blanking unit 61. As shown in FIG. 3, the electron beam EB emitted from the electron gun 30 is shaped by a lens 41 so as to be parallel to a vertical axis. The electron beam EB shaped in parallel enters a circular area C1 indicated by a virtual line. Some of the electron beams EB incident on the region C1 are blocked by the aperture 51, and the remaining electron beams pass through the opening Hmn of the aperture 51. As a result, the electron beam EB is divided (multiplied) into 64 electron beams traveling vertically downward.

  In the present embodiment, an electron beam that has passed through the opening Hmn of the aperture 51 is indicated as an electron beam EBmn. Note that FIG. 3 representatively shows only the electron beams EB11, EB18, EB81, and EB88 that have passed through the openings H11, H18, H81, and H88.

  The blanking unit 61 is a unit for blanking each of the electron beams EBmn individually. FIG. 4 is a plan view of the blanking unit 61. As shown in FIG. 4, the blanking unit 61 has a substrate 610 and 64 blankers BK provided on the upper surface (the surface on the + Z side) of the substrate 610.

  The substrate 610 is a square substrate made of, for example, silicon. In the substrate 610, 64 openings HH are formed in a matrix of 8 rows and 8 columns. Each of the 64 openings HH is positioned so as to be located below the opening H formed in the aperture 51. In the present embodiment, the opening HH located immediately below the opening Hmn is referred to as an opening HHmn.

  The opening HHmn is slightly larger than the opening Hmn, and the electron beam EBmn that has passed through the opening Hmn can pass through the opening HHmn without interfering with the substrate 610.

  FIG. 5 is an enlarged perspective view showing the blanker BK. The blanker BK includes a pair of electrodes 611 and 612 made of a metal such as copper. The electrode 611 is a member having a U-shaped XY cross section, for example. The electrodes 611 are arranged along the outer edges on the + X side and -X side and the outer edge on the + Y side of the opening HHmn provided in the substrate 610. The electrode 612 is a plate-shaped electrode and is arranged along the outer edge of the opening HHmn on the −Y side. Therefore, as can be seen from FIG. 5, the electron beam EBmn passing through the aperture 51 passes between the electrodes 611 and 612 constituting the blanker BK and enters the opening HHmn of the substrate 610.

  As shown in FIGS. 3 and 4, a blanker BK is provided in each opening HHmn. In the present embodiment, the blanker BK provided in the opening HHmn is referred to as a blanker BKmn.

  The electrode 611 is grounded via a circuit (not shown) provided on the substrate 610. The electrode 612 is connected to the blanking amplifier 104 included in the control system 100 via a circuit (not shown) provided on the substrate 610. When a voltage is applied to the electrode 612 by the blanking amplifier 104, the electron beam EBmn incident on the opening HHmn of the substrate 610 is deflected in the direction indicated by the arrow in FIG. Thereby, as shown in FIG. 1, the electron beam EBmn is shielded by the aperture 52, and the electron beam EBmn is in a blanked state.

  The lens 42 is an annular electromagnetic lens, and is disposed below the blanking unit 61. The lens 42 focuses the 64 electron beams EBmn, which pass through the blanking unit 61 and travel downward in parallel with each other, near the aperture 52.

  The aperture 52 is a plate-shaped member provided with an opening through which the electron beam EBmn passes. The aperture 52 is arranged near a convergence point (crossover point) of the electron beam EBmn passing through the lens 42. As each electron beam EBmn passes through the opening of the aperture 52, the shot shape of each electron beam EBmn is shaped. When the electron beam EBmn is deflected by the blanker BK of the blanking unit 61, the electron beam EBmn is blanked by the aperture 51.

  The deflector 62 is disposed below the aperture 52. The deflector 62 has a plurality of pairs of electrodes arranged to face each other. The deflector 62 deflects the electron beam EBmn that has passed through the aperture 52 according to the voltage applied to the electrode. In the present embodiment, for convenience of explanation, only a pair of electrodes arranged at a predetermined distance in the X-axis direction is shown in the drawing. The deflector 62 can deflect the electron beam EBmn in the X-axis direction and the Y-axis direction.

  The lens 43 is an annular electromagnetic lens arranged so as to surround the deflector 62. The lens 43 focuses the electron beam EBmn on a desired position of the sample 120 placed on the stage 70 by cooperating with the deflector 62.

  The stage 70 is arranged inside the lighting chamber 80a. The stage 70 is a stage that can move at least in a horizontal plane while holding the sample 120 on which a pattern is to be written substantially horizontally. On the upper surface of the stage 70, a mirror Mx whose longitudinal direction is the Y-axis direction and a mirror My whose longitudinal direction is the X-axis direction are provided. The position of the stage 70 in the horizontal plane is detected with reference to the mirrors Mx and My.

  The control system 100 is a system for controlling the irradiation device 20 and the stage 70. The control system 100 includes a control device 101, a power supply device 102, a lens driving device 103, a blanking amplifier 104, a deflection amplifier 105, and a stage driving device 106.

  FIG. 6 is a block diagram of the control device 101. As shown in FIG. 6, the control device 101 includes a CPU (Central Processing Unit) 101a, a main storage unit 101b, an auxiliary storage unit 101c, an input unit 101d, a display unit 101e, an interface unit 101f, and a system for connecting the above units. It is a computer having a bus 101g.

  The CPU 101a reads and executes a program stored in the auxiliary storage unit 101c. Then, the devices constituting the control system 100 are comprehensively controlled according to the program.

  The main storage unit 101b has a volatile memory such as a RAM (Random Access Memory). The main storage unit 101b is used as a work area of the CPU 101a.

  The auxiliary storage unit 101c has a nonvolatile memory such as a ROM (Read Only Memory), a magnetic disk, and a semiconductor memory. The auxiliary storage unit 101c stores programs executed by the CPU 101a and various parameters. Further, evaluation data for determining the processing accuracy of the aperture 51 is stored. This evaluation data is data that defines an evaluation pattern drawn on the sample 120. The evaluation pattern will be described later.

  The input unit 101d has a keyboard and a pointing device such as a mouse. The user's instruction is input via the input unit 101d and is notified to the CPU 101a via the system bus 101g.

  The display unit 101e has a display unit such as an LCD (Liquid Crystal Display). The display unit 101e displays, for example, information on the status of the electron beam drawing apparatus 10, drawing patterns, and the like.

  The interface unit 101f includes a LAN interface, a serial interface, a parallel interface, an analog interface, and the like. The power supply device 102, the lens driving device 103, the blanking amplifier 104, the deflection amplifier 105, and the stage driving device 106 are connected to the control device 101 via the interface unit 101f.

  The control device 101 configured as described above controls the power supply device 102, the lens driving device 103, the blanking amplifier 104, the deflection amplifier 105, and the stage driving device 106 as a whole.

  Returning to FIG. 1, the power supply device 102 applies a voltage to the electron gun 30 based on an instruction from the control device 101. Thereby, the electron beam EB is emitted downward from the electron gun 30.

  The lens driving device 103 controls the power (refractive power) of the lens 41 with respect to the electron beam EB based on an instruction from the control device 101, and causes the electron beam EB that spreads downward to travel in parallel with the vertical axis. Shape into an electron beam. The lens driving device 103 controls the power of the lens 42 to focus the electron beam EBmn toward the center of the aperture 52, and controls the power of the lens 43 so that the electron beam EBmn is focused on the upper surface of the sample 120. Get focus.

  The blanking amplifier 104 generates a blanking signal for each of the 64 blankers BK included in the blanking unit 61 based on an instruction from the control device 101. Then, the generated blanking signal is output to the electrode 612 of each blanker BK. For example, the blanking signal is a binary signal of a high level and a low level. When the blanking signal output to the electrode 612 of the blanker BK is at a high level, the electron beam EBmn is blanked. Therefore, a desired pattern can be drawn on the sample 120 by outputting the blanking signal modulated based on the drawing pattern to each blanker BK. Further, by outputting the voltage signal maintained at the high level to the desired blanker BK, the desired electron beam EBmn can be brought into a blanked state.

  The deflection amplifier 105 generates a voltage signal based on an instruction from the control device 101, and outputs the voltage signal to an electrode included in the deflector 62. This causes a potential difference between the electrodes of the deflector 62. The electron beam EBmn passing through the deflector 62 is deflected by an amount corresponding to the potential difference.

  The stage driving device 106 measures the positions of the mirrors Mx and My of the stage 70 using a laser sensor (not shown) or the like, and detects the position of the stage 70 based on the measurement result. Then, the stage driving device 106 drives the stage 70 based on an instruction from the control device 101, and moves and positions the sample 120.

  In the above-described electron beam lithography apparatus 10, the power supply device 102, the lens driving device 103, the blanking amplifier 104, the deflection amplifier 105, and the stage driving device 106 are totally controlled by the control device 101. For example, when drawing a pattern on the sample 120 using the electron beam lithography apparatus 10, the CPU 101 a of the control device 101 drives the stage 70 on which the sample 120 is mounted, and places the sample 120 below the irradiation device 20. Position.

  Next, the CPU 101a drives the power supply device 102 to apply a voltage to the electron gun 30. Thereby, the electron beam EB is emitted from the electron gun 30.

  When the electron beam EB is emitted from the electron gun 30, the CPU 101a controls the lens 41 via the lens driving device 103 to shape the electron beam EB spreading downward so as to be parallel to the vertical axis.

  The electron beam EB shaped by the lens 41 travels downward and passes through the aperture 51. Thereby, the electron beam EB is branched, and a plurality (64) of electron beams EBmn are generated. These electron beams EBmn pass through the opening HHmn of the substrate 610 constituting the blanking unit 61 via the blanker BKmn of the blanking unit 61.

  The CPU 101 a controls the lens 42 via the lens driving device 103 to focus each of the electron beams EBmn passing through the blanking unit 61 near the opening of the aperture 52.

  Each of the electron beams EBmn passes through the opening of the aperture 52 to shape the outer diameter and shape of the shot. Then, the electron beam EBmn that has passed through the aperture 52 enters the lens 43.

  The CPU 101 a controls the lens 43 via the lens driving device 103 to focus the electron beam EBmn incident on the lens 43 on the surface of the sample 120 held on the stage 70. Further, the CPU 101a deflects the electron beam EBmn in the X-axis direction or the Y-axis direction via the deflection amplifier 105, and controls the incident position of the electron beam EBmn on the sample 120.

  In parallel with the above operation, the CPU 101a inputs a blanking signal modulated based on a pattern to be drawn to each blanker BKmn via a blanking amplifier 104. Thereby, the electron beam EBmn is deflected at a predetermined timing, and blanking for the electron beam EBmn is executed intermittently.

  In the electron beam drawing apparatus 10, the sample 120 is exposed by the electron beam EBmn modulated by the drawing pattern by the cooperation of the blanking amplifier 104 and the deflection amplifier 105 as described above, and the pattern is drawn on the sample 120. You.

<< Evaluation pattern drawing process >>
Next, an evaluation pattern drawing process for evaluating the accuracy of the aperture 51 used in the electron beam drawing apparatus 10 will be described. This evaluation pattern is a pattern for evaluating the processing accuracy of the aperture.

  The flowchart of FIG. 7 shows a series of processing executed by the CPU 101a according to the program stored in the auxiliary storage unit 101c. The evaluation pattern drawing process is performed according to the flowchart shown in FIG. Hereinafter, the evaluation pattern drawing process will be described with reference to the flowchart of FIG.

  First, the CPU 101a reads the evaluation data stored in the auxiliary storage unit 101c (Step S101). FIG. 8 is a diagram showing an SEM (Scanning Electron Microscope) image Ph0 of the evaluation pattern P0 drawn based on the evaluation data. The evaluation data is data for drawing an evaluation pattern P0 including square marks Mmn arranged in a matrix of 8 rows and 8 columns, for example, as shown in FIG. Each mark Mmn corresponds to the opening Hmn of the aperture 51 shown in FIG.

  In the electron beam lithography apparatus 10, one crossover point of the electron beam EBmn exists between the electron gun 30 and the sample 120 as shown in FIG. Therefore, the arrangement of the marks Mmn of the evaluation pattern P0 is symmetric with respect to the X-axis and the Y-axis with respect to the arrangement of the openings Hmn of the aperture 51 shown in FIG. That is, as shown in FIG. 2, the marks M11 to M18 formed by the electron beams EB11 to EB18 via the openings H11 to H18 which are located closest to the + Y side and are arranged in the + X direction in order are shown in FIG. As shown, it is located at the most -Y side and is arranged in the -X direction. In FIG. 8, for convenience of explanation, the XY coordinate system is rotated by 180 degrees, and the arrangement of the marks Mmn is displayed so as to match the arrangement of the openings Hmn in FIG. The marks M21 to M28 formed by the electron beams EB21 to EB28 via the openings H21 to H28 are arranged on the + Y side of the marks M11 to M18. Similarly, marks M31 to M38, marks M41 to M48, marks M51 to M58, marks M61 to M68, marks M71 to M78, and marks M81 to M88 are sequentially arranged in the + Y direction.

  For this reason, in the present embodiment, the mark located on the first line closest to the −Y side is displayed as M1n. Then, the marks located on the second to eighth lines are displayed as M2n to M8n. Further, the mark located in the first column on the + X side is displayed as Mm1. Then, the marks located in the second to eighth columns are displayed as Mm2 to Mm8.

  Next, the CPU 101a draws the evaluation pattern P0 using all the electron beams EBmn that have passed through the aperture 51 without blanking the electron beam EBmn (step S102). In this case, one mark Mmn is drawn by one electron beam EBmn. The irradiation time of each electron beam EBmn incident on the sample 120 when drawing the mark Mmn is a constant value Td0.

When it is assumed that a drawing error or the like does not occur at the time of drawing a pattern, or when the shape and dimensions of the opening Hmn of the aperture 51 are as designed, the marks Mmn of the evaluation pattern P0 are shown in FIG. As shown, they are equal in size to each other and are arranged at predetermined intervals. The reason is that, when there is no variation in the shape and the like of the opening Hmn of the aperture 51, the dose of each electron beam EBmn becomes constant at f (Td0) mc / cm ² . However, for example, when the area of the opening of the aperture 51 varies, the size and shape of the mark Mmn also vary.

  For example, as shown in FIG. 9, the opening Hmn completed as designed is rectangular. However, the thickness of the plating film on the surface of the aperture 51 may be uneven, or the shape of the opening may be elliptical, such as the openings E1 to E4 shown as an example, depending on the processing error of the base material of the aperture 51, or may be large. May differ from the designed aperture. When openings such as the openings E1 to E4 are formed in the aperture 51, the dose of each electron beam EBmn varies, and, for example, the area of the electron beam EBmn is different from that of the evaluation pattern P0 shown in the SEM image Ph0 of FIG. Marks M37, M76, and M78 that are larger than the mark or a mark M88 that has a smaller area than the other marks.

  Next, as shown in FIG. 11, the CPU 101a divides the aperture 51 into a plurality of areas (Step S103). The aperture 51 is provided with 64 openings Hmn. Therefore, the aperture 51 is divided into four regions A1 to A4 so that each region includes 16 openings Hmn.

  As shown in FIG. 11, the region A1 includes openings H11 to H14, H21 to H24, H31 to H34, and H41 to H44. The region A2 includes openings H51 to H54, H61 to H64, H71 to H74, and H81 to H84. The region A3 includes openings H15 to H18, H25 to H28, H35 to H38, and H45 to H48. The region A4 includes openings H55 to H58, H65 to H68, H75 to H78, and H85 to H88.

  Next, the CPU 101a draws an evaluation pattern using the area A1 of the aperture 51 (step S104). To write an evaluation pattern using the region A1, for example, the electron beams EBmn other than the electron beams EBmn passing through the openings H11 to H14, H21 to H24, H31 to H34, and H41 to H44 are blanked. Then, the evaluation pattern P1 based on the evaluation data is drawn using the 16 electron beams EB11 to EB14, EB21 to EB24, EB31 to EB34, and EB41 to EB44. The evaluation pattern P1 is a pattern based on the evaluation data that defines the evaluation pattern P0. Therefore, ideally, the marks constituting the evaluation pattern P1 have the same size as the marks of the evaluation pattern P0, and are arranged at the same pitch.

  To write the evaluation pattern P1, as shown in FIG. 12, first, a mark group MG1 including 16 marks arranged in a matrix of 4 rows and 4 columns is drawn. Here, each mark is simultaneously drawn using 16 electron beams EB11 to EB14, EB21 to EB24, EB31 to EB34, EB41 to EB44.

  In a similar manner, as shown in FIG. 13, the mark group MG2 is drawn on the + Y side of the mark group MG1, and as shown in FIG. 14, the mark group MG3 is drawn on the -X side of the mark group MG1. Then, as shown in FIG. 15, the mark group MG4 is drawn on the −X side of the mark group MG2.

  FIG. 16 is a diagram showing an SEM image Ph1 of the evaluation pattern P1. As shown in FIG. 16, by drawing the mark groups MG1 to MG4 as described above, the evaluation pattern P1 including the mark groups MG1 to MG4 is drawn. In the evaluation pattern P1, each of the mark groups MG1 to MG4 includes 16 marks M11 to M14, M21 to M24, M31 to M34, and 16 marks drawn by the electron beams EB11 to EB14, EB21 to EB24, EB31 to EB34, and EB41 to EB44. M41 to M44.

  Next, the CPU 101a draws an evaluation pattern using the area A2 of the aperture 51 (Step S105). To write an evaluation pattern using the area A2, for example, the electron beams EBmn other than the electron beams EBmn passing through the openings H51 to H54, H61 to H64, H71 to H74, and H81 to H84 are blanked. Then, similarly to the drawing of the evaluation pattern P1, the evaluation pattern P2 based on the evaluation data is drawn using the 16 electron beams EB51 to EB54, EB61 to EB64, EB71 to EB74, and EB81 to EB84.

  FIG. 17 is a diagram illustrating an SEM image Ph2 of the evaluation pattern P2. As shown in FIG. 17, by drawing the mark groups MG1 to MG4 in the manner described above, the evaluation pattern P2 including the mark groups MG1 to MG4 is drawn. In the evaluation pattern P2, each of the mark groups MG1 to MG4 includes 16 marks M51 to M54, M61 to M64, M71 to M74, and 16 marks drawn by the electron beams EB51 to EB54, EB61 to EB64, EB71 to EB74, EB81 to EB84. M81 to M84.

  Next, the CPU 101a draws an evaluation pattern using the area A3 of the aperture 51 (step S106). To write an evaluation pattern using the region A3, for example, the electron beams EBmn other than the electron beams EBmn passing through the openings H15 to H18, H25 to H28, H35 to H38, and H45 to H48 are blanked. Then, similarly to the drawing of the evaluation patterns P1 and P2, the evaluation pattern P3 based on the evaluation data is drawn using the 16 electron beams EB15 to EB18, EB25 to EB28, EB35 to EB38, and EB45 to EB48.

  FIG. 18 is a diagram showing an SEM image Ph3 of the evaluation pattern P3. As shown in FIG. 18, by drawing the mark groups MG1 to MG4 in the manner described above, the evaluation pattern P3 including the mark groups MG1 to MG4 is drawn. In the evaluation pattern P3, each of the mark groups MG1 to MG4 has 16 marks M15 to M18, M25 to M28, M35 to M38 drawn by the electron beams EB15 to EB18, EB25 to EB28, EB35 to EB38, and EB45 to EB48. M45-M48.

  Next, the CPU 101a draws an evaluation pattern using the area A4 of the aperture 51 (Step S107). To write an evaluation pattern using the region A4, for example, the electron beams EBmn other than the electron beams EBmn passing through the openings H55 to H58, H65 to H68, H75 to H78, and H85 to H88 are blanked. Then, similarly to the drawing of the evaluation patterns P1 to P3, the evaluation pattern P4 based on the evaluation data is drawn using the 16 electron beams EB55 to EB58, EB65 to EB68, EB75 to EB78, and EB85 to EB88.

  FIG. 19 is a diagram illustrating an SEM image Ph4 of the evaluation pattern P4. As shown in FIG. 19, by writing the mark groups MG1 to MG4 in the above-described manner, the evaluation pattern P4 including the mark groups MG1 to MG4 is drawn. In the evaluation pattern P4, each of the mark groups MG1 to MG4 has 16 marks M55 to M58, M65 to M68, M75 to M78, and 16 marks drawn by the electron beams EB55 to EB58, EB65 to EB68, EB75 to EB78, EB85 to EB88. M85-M88.

  When the drawing of the evaluation patterns P0 to P4 ends, the CPU 101a ends the evaluation pattern drawing processing. When the evaluation pattern drawing process is completed, the evaluation patterns P0 to P4 are drawn on the sample 120.

《Evaluation processing》
Next, an evaluation process for evaluating the accuracy of the aperture 51 using the evaluation patterns P0 to P4 drawn on the sample 120 will be described. The evaluation process is a process for evaluating the accuracy of the aperture 51 based on the SEM images of the evaluation patterns P0 to P4. This evaluation process is executed by, for example, the CPU 101a of the control device 101.

  The SEM images Ph0 to Ph4 of the evaluation patterns P0 to P4 used in the evaluation processing are generated by photographing the evaluation patterns P0 to P4 drawn on the sample 120 by an apparatus such as an SEM. These SEM images Ph0 to Ph4 are stored in the auxiliary storage unit 101c of the control device 101 in advance.

  The flowchart of FIG. 20 shows a series of processes executed by the CPU 101a according to the program stored in the auxiliary storage unit 101c. The evaluation process is performed according to the flowchart shown in FIG. Hereinafter, the evaluation processing will be described with reference to the flowchart in FIG.

  First, the CPU 101a reads the SEM images Ph0 and Ph1 stored in the auxiliary storage unit 101c. Then, the SEM image Ph0 and the SEM image Ph1 are compared to generate a difference image Df1 (Step S201).

  In the comparison between the SEM images, the CPU 101a first matches the SEM image Ph0 with the SEM image Ph1. The SEM image matching calculates the normalized cross-correlation of the SEM image Ph1 while relatively moving the SEM image Ph1 with respect to the SEM image Ph0. Then, based on the calculation result, the SEM image Ph0 and the SEM image Ph1 are superimposed. In this state, the 64 marks of the SEM image Ph0 and the 64 marks of the SEM image Ph1 are accurately overlapped. Next, the CPU 101a generates a difference image Df1 between the SEM image Ph0 and the SEM image Ph1. The SEM image is a black and white image, but the difference image Df1 may be binarized as necessary.

  FIG. 21 is a diagram illustrating the difference image Df1. When the size of the mark image of the SEM image Ph0 is different from the size of the mark image of the SEM image Ph1, the difference image Df1 is, for example, an image in which the marks MM37, MM76, MM78, MM88, and the like appear. Becomes The area of each of the marks MM37, MM76, MM78, and MM88 indicates the difference between the area of the corresponding mark of the SEM image Ph0 and the area of the mark of the SEM image Ph1.

  Next, the CPU 101a evaluates the aperture 51 based on the difference image Df1 (Step S202).

  In the evaluation of the aperture 51, as shown in FIG. 22, the CPU 101a divides the difference image Df1 into four equal parts by a straight line passing through the center of the difference image Df1 and parallel to the Y-axis and the X-axis, and the four regions AA1 to AA4 Is specified. The positions of the regions AA1 to AA4 correspond to the regions A1 to A4 of the aperture 51 shown in FIG. Next, the CPU 101a calculates the total value AT1 to AT4 of the mark area for each of the areas AA1 to AA4.

  For example, in the example shown in FIG. 22, the total values AT1 and AT2 of the areas AA1 and AA2 where no mark exists are almost zero, but the total values AT3 and AT4 of the areas AA3 and AA4 where the mark exists are zero or more. become. Thus, the CPU 101a compares the total values AT1 to AT4 with a preset threshold Th. Then, an area in which the total value AT1 to AT4 is equal to or larger than the threshold is specified as a defective area. For example, when the total values AT3 and AT4 are equal to or larger than the threshold Th1, the areas AA3 and AA4 are specified as defective areas. The threshold value Th can be appropriately determined according to the specifications and purpose of the electron beam lithography apparatus 10.

  Note that the evaluation pattern P0 shown in the SEM image Ph0 that is the basis of the difference image Df1 is drawn with 64 electron beams EBmn, and the evaluation pattern P1 shown in the SEM image Ph1 is a pattern of 64 electron beams EBmn. These are drawn by 16 of the electron beams EB11 to EB14, EB21 to EB24, EB31 to EB34, EB41 to EB44. Therefore, for the difference image Df1, the appearance of the mark M in the area AA1 cannot usually occur.

  Therefore, in the evaluation using the difference image Df1, the spot shape of the electron beam EBmn passing through the region A1 of the aperture 51 is compared with the spot shape of the electron beam EBmn passing through the regions A2 to A4 of the aperture 51. Become. Therefore, in the evaluation using the difference image Df1, the evaluation of the aperture 51 based on the deviation between the opening Hmn formed in the region A1 of the aperture 51 and the opening Hmn formed in the regions A2, A3, and A4 is performed.

  Next, the CPU 101a reads the SEM images Ph0 and Ph2 stored in the auxiliary storage unit 101c. Then, similarly, the CPU 101a compares the SEM image Ph0 and the SEM image Ph2 to generate a difference image Df2 (Step S203).

  Next, the CPU 101a evaluates the aperture 51 based on the difference image Df2 (Step S204). Thus, the evaluation of the aperture 51 based on the deviation between the opening Hmn formed in the region A2 of the aperture 51 and the opening Hmn formed in the regions A1, A3, and A4 is performed.

  Similarly, the CPU 101a compares the SEM image Ph0 and the SEM image Ph3 to generate a difference image Df3 (Step S205), and evaluates the aperture 51 based on the difference image Df3 (Step S206). Thus, the evaluation of the aperture 51 based on the deviation between the opening Hmn formed in the region A3 of the aperture 51 and the opening Hmn formed in the regions A1, A2, A4 is performed.

  Subsequently, the CPU 101a compares the SEM image Ph0 and the SEM image Ph4 to generate a difference image Df4 (Step S207), and evaluates the aperture 51 based on the difference image Df4 (Step S208). Thus, the evaluation of the aperture 51 based on the deviation between the opening Hmn formed in the region A4 of the aperture 51 and the opening Hmn formed in the regions A1, A2, and A3 is performed.

  FIG. 23 is a diagram conceptually showing evaluation using the difference images Df1 to Df4. As shown in FIG. 23, the evaluation results for the areas A1 to A4 of the aperture 51 corresponding to the areas AA1 to AA4 of the difference images Df1 to Df4 are obtained by the processing of steps S201 to S208.

  Next, the CPU 101a determines whether or not the aperture 51 can be used based on the evaluation results for the areas A1 to A4 of the aperture 51 (step S209).

  When the aperture 51 is divided into four regions A1 to A4, each region is evaluated three times. For example, for the area A1, three evaluations are performed in comparison with the areas A2 to A4. The CPU 101a determines that the aperture 51 in which the area determined to be unusable in all three evaluations reaches a majority is unusable. In the example shown in FIG. 23, the areas A3 and A4 are determined to be unusable in all three evaluations. Therefore, the CPU 101a determines that the two areas A3 and A4 of the four areas A1 to A4 cannot be used, and consequently determines that the aperture 51 cannot be used. .

  When determining whether or not the aperture 51 can be used, the CPU 101a displays the determination result on the display unit 101e (step S210). When the processing in step S210 is completed, the CPU 101a ends the evaluation processing.

  The user can replace or maintain the aperture 51 based on the evaluation result of the aperture 51. However, depending on the evaluation result, there is a case where the aperture 51 determined to be unusable can be continuously used by correcting the dose amount of the electron beam. Hereinafter, the correction processing of the dose amount of the electron beam will be described.

《Correction processing》
The flowchart of FIG. 24 shows a series of processes executed by the CPU 101a according to the program stored in the auxiliary storage unit 101c. The correction process is performed according to the flowchart shown in FIG. Hereinafter, the correction processing will be described with reference to the flowchart in FIG.

  First, the CPU 101a determines the design area SD of the opening Hmn of the aperture 51 and the areas S1 (1) to S1 (16) of the marks M11 to M14, M21 to M24, M31 to M34, and M41 to M44 of the SEM image Ph1. ) And D1 (1) to D1 (16) are calculated (step S301).

  Specifically, first, the CPU 101a reads the SEM image Ph1 from the auxiliary storage unit 101c. Then, the areas S1 (1) to S1 (16) of the marks M11 to M14, M21 to M24, M31 to M34, and M41 to M44 of the SEM image Ph1 are measured. Then, the area S1 (i) is subtracted from the designed area SD. Note that i is an integer of 1 to 16, and the differences D1 (1) to D1 (16) are represented by the following equation (1).

  D1 (i) = SD−S1 (i) (1)

  Next, the CPU 101a uses the differences D1 (1) to D1 (16) to correct the irradiation times of the electron beams EB11 to EB14, EB21 to EB24, EB31 to EB34, and EB41 to EB44 CV1 (1) to CV1 ( 16) is calculated (step S302).

  When the design area of the opening Hmn provided in the aperture 51 is SD, when the electron beam EBmn is irradiated for a time Td0, the dose V is proportional to the product (SD · Td0) of the area SD of the opening and the time Td0. Value. Therefore, when the target irradiation time is Td0, the correction value CV1 (i) can be obtained by the following equation (2).

CV1 (i) = Td0 · (SD−S1 (i)) / S1 (i)
= Td0 · D1 (i) / S1 (i) (2)

  Next, the CPU 101a calculates the irradiation time Td1 (i) of each of the electron beams EB11 to EB14, EB21 to EB24, EB31 to EB34, and EB41 to EB44 in consideration of the correction value (step S303). The irradiation time Td1 (i) can be obtained by the following equation (3).

  Td1 (i) = Td0 + CV1 (i) (3)

  Next, the CPU 101a reads the SEM images Ph1 and Ph2 from the auxiliary storage unit 101c. Then, by comparing the SEM images Ph1 and Ph2, the area S1 (i) of the marks M11 to M14, M21 to M24, M31 to M34, and M41 to M44 of the SEM image Ph1, and the marks M51 to M54 and M61 of the SEM image Ph2. The difference D2 (i) between the area S2 (i) of the data M64, M71 to M74, and M81 to M84 is calculated (step S304). The difference D2 (i) is expressed by the following equation (4).

  D2 (i) = S1 (i) -S2 (i) (4)

  Next, the CPU 101a calculates the correction value CV2 (i) of the irradiation time of the electron beams EB51 to EB54, EB61 to EB64, EB71 to EB74, EB81 to EB84 using the difference D2 (i) (step S305). The correction value CV2 (i) can be obtained by the following equation (5).

  CV2 (i) = Td1 (i) · D2 (i) / S2 (i) (5)

  Next, the CPU 101a calculates the irradiation time Td3 (i) of each of the electron beams EB15 to EB18, EB25 to EB28, EB35 to EB38, and EB45 to EB48 in consideration of the correction value (step S306). The irradiation time Td2 (i) can be obtained by the following equation (6).

  Td2 (i) = Td1 (i) + CV2 (i) (6)

  Next, the CPU 101a reads the SEM images Ph1 and Ph3 from the auxiliary storage unit 101c. Then, by comparing the SEM images Ph1 and Ph3, the area S1 (i) of the marks M11 to M14, M21 to M24, M31 to M34, and M41 to M44 of the SEM image Ph1, and the marks M15 to M18 and M25 of the SEM image Ph3. The difference D3 (i) between the areas S3 (i) of the blocks M28, M35 to M38, and M45 to M48 is calculated (step S307). The difference D3 (i) is expressed by the following equation (7).

  D3 (i) = S1 (i) -S3 (i) (7)

  Next, using the difference D3 (i), the CPU 101a calculates a correction value CV3 (i) of the irradiation time of the electron beams EB15 to EB18, EB25 to EB28, EB35 to EB38, EB45 to EB48 (step S308). The correction value CV3 (i) can be obtained by the following equation (8).

  CV3 (i) = Td1 (i) · D3 (i) / S3 (i) (8)

  Next, the CPU 101a calculates the irradiation time Td4 (i) of each of the electron beams EB15 to EB18, EB25 to EB28, EB35 to EB38, and EB45 to EB48 in consideration of the correction value (step S309). The irradiation time Td3 (i) can be obtained by the following equation (9).

  Td3 (i) = Td1 (i) + CV3 (i) (9)

  Next, the CPU 101a reads the SEM images Ph1 and Ph4 from the auxiliary storage unit 101c. Then, by comparing the SEM images Ph1 and Ph4, the area S1 (i) of the marks M11 to M14, M21 to M24, M31 to M34, and M41 to M44 of the SEM image Ph1, and the marks M55 to M58 and M65 of the SEM image Ph4. The difference D4 (i) between the areas S4 (i) of M68, M75 to M78, and M85 to M88 is calculated (step S310). The difference D4 (i) is expressed by the following equation (10).

  D4 (i) = S1 (i) -S4 (i) (10)

  Next, the CPU 101a calculates the correction value CV4 (i) of the irradiation time of the electron beams EB55 to EB58, EB65 to EB68, EB75 to EB78, EB85 to EB88 using the difference D4 (i) (step S311). The correction value CV4 (i) can be obtained by the following equation (11).

  CV4 (i) = Td1 (i) · D4 (i) / S4 (i) (11)

  Next, the CPU 101a calculates the irradiation time Td4 (i) of each of the electron beams EB55 to EB58, EB65 to EB68, EB75 to EB78, and EB85 to EB88, taking into account the correction value (step S312). The irradiation time Td4 (i) can be obtained by the following equation (12).

  Td4 (i) = Td1 (i) + CV4 (i) (12)

  The irradiation times Td1 (i) to Td4 (i) obtained by the processing in steps S301 to S312 are as follows. That is, the irradiation time of the area A1 of the aperture 51 is obtained by adding the design value of the opening Hmn and the correction value CV1 (i) obtained from the actually measured value of the opening Hmn of the area A1 to the design irradiation time Td0 defined by the design value. It will be. The irradiation time of the regions A2, A3, and A4 is obtained by adding the correction value CV1 (i) to the design irradiation time Td0, and furthermore, the correction value CV2 (i) of the opening Hmn of the regions A2, A3, and A4 with respect to the opening Hmn of the region A1. ), CV3 (i) and CV4 (i).

Td1 (i) = Td0 + CV1 (i)
Td2 (i) = Td1 (i) + CV2 (i)
= Td0 + CV1 (i) + CV2 (i)
Td3 (i) = Td1 (i) + CV3 (i)
= Td0 + CV1 (i) + CV3 (i)
Td4 (i) = Td1 (i) + CV4 (i)
= Td0 + CV1 (i) + CV4 (i)

  After calculating the corrected irradiation times Td1 (i) to Td4 (i) with respect to the target irradiation time Td0 defined by the drawing data for each of the 64 electron beams EBmn, the CPU 101a calculates the irradiation times Td1 (i) to Td4. (I) is stored in the auxiliary storage unit, and the correction processing ends.

  In drawing the pattern, the electron beam drawing apparatus 10 uses the irradiation times Td1 (i) to Td4 (i) corresponding to the area of the opening Hmn of the aperture 51 from the target irradiation time Td0 of the electron beam defined by the drawing data. ) Is calculated. Then, the electron beam EBmn is irradiated based on the calculated irradiation times Td1 (i) to Td4 (i). Thus, even if the size of the opening Hmn of the aperture 51 varies, the electron beam EBmn can be incident on the sample 120 so as to have a dose based on the design value.

  As described above, in the present embodiment, the aperture 51 is divided into a plurality of areas A1 to A4 (step S103). Then, the SEM images Ph1 to Ph0 of the evaluation patterns P1 to P4 drawn using the areas A1 to A4 of the aperture 51 are compared (steps S201, S203, S205, S207), and based on the comparison result, the SEM images of the aperture 51 are determined. A determination is made as to whether or not use is possible.

  Therefore, for example, as compared with the case where the area and dimensions are individually measured for the openings Hmn of the apertures 51 and the use of the apertures is determined based on the measured results, the accuracy is extremely short. It is often possible to determine whether the aperture can be used.

  Further, it is possible to avoid the use of the aperture determined to be unusable according to the determination of whether the aperture can be used. Therefore, the electron beam can be multiplied with high accuracy by using an aperture with high processing accuracy, and a pattern can be drawn with high accuracy.

  Further, in the present embodiment, as can be seen with reference to FIG. 23, for the regions A1 to A4 of the aperture 51, a region having a processing error and a region having no processing error are determined. Therefore, the defect rate of the aperture 51 can be grasped. The defect rate is represented by, for example, a ratio (= TM2 / TM1) of the total number TM1 of the areas and the total number TM2 of the areas having the processing error.

  In the present embodiment, the aperture 51 is evaluated based on the SEM images Ph0 to Ph4 of the evaluation patterns P0 to P4 drawn on the sample 120. Therefore, the evaluation of the aperture 51 can be performed without stopping the electron beam lithography apparatus 10.

  In the present embodiment, for example, by writing the evaluation patterns P0 to P4 together with the original image pattern on the sample 120, it is possible to evaluate the aging of the aperture 51 due to the influence of contamination or the like every time the original image pattern is drawn. .

  In the present embodiment, the variation of the dose due to the variation of the area of the opening Hmn provided in the aperture 51 is adjusted by the correction processing (Steps S301 to S312). Therefore, a pattern can be drawn on the sample 120 with high accuracy.

  In the present embodiment, for example, as shown in FIG. 25, even if there is a defective opening with a low processing accuracy such as an opening with a significantly large area or an opening with a significantly small area in the aperture 51, When the distribution of these defective openings is equal, for example, the aperture 51 is determined to be usable in all the areas A1 to A4, and as a result, it is determined that the aperture 51 is usable.

  However, in the present embodiment, since the correction processing of the aperture 51 is performed, even in such a case, it is possible to draw a pattern with high accuracy. Further, in the correction processing, when the irradiation time in design and the irradiation time after correction are significantly different, it is possible to determine that the aperture 51 cannot be used. Accordingly, it is possible to avoid drawing a pattern with the aperture 51 having low processing accuracy.

  In the present embodiment, the case where apertures are formed in the aperture 51 in a matrix of 8 rows and 8 columns has been described. The arrangement of the openings of the aperture 51 is not limited to this. When the openings of the aperture 51 are arranged in a matrix of odd rows or odd columns, an area that partially overlaps the aperture 51 may be defined as shown in FIG. .

≪Second implementation mobile phone≫
Next, a second embodiment will be described. The electron beam lithography apparatus 10 according to the second embodiment differs from the electron beam lithography apparatus 10 according to the first embodiment in that a dose amount caused by an electron beam shot is corrected. Hereinafter, an electron beam lithography apparatus 10 according to a second embodiment will be described with reference to the drawings. In addition, about the structure same as or equivalent to 1st Embodiment, while using the same code | symbol, the description is abbreviate | omitted or simplified.

  The dose by the electron beam EBmn may be different for each electron beam EBmn. Therefore, a dose error occurs between the electron beams EBmn. Therefore, processing for correcting an error between the electron beams EBmn is required.

  Since the dose of the electron beam is proportional to the irradiation time of the electron beam, the error of the dose increases or decreases depending on the response speed of the blanker BKmn. For example, the rise time and fall time of the blanking signal output from the blanking amplifier 104 to the blanker BKmn are affected by the wiring route, the wiring length to the blanking amplifier 104, the wiring route, and the like. Therefore, even if the blanking amplifier 104 outputs a blanking signal to each blanker BKmn based on the target dose, a difference occurs between the actual dose and the target dose. Since this difference is different for each blanker BKmn, a dose error occurs between the electron beams EBmn passing through the blanker BKmn.

  The dose error appears as a difference in the size of the mark drawn by the electron beam. For example, when writing a mark on the sample 120, the sample 120 is irradiated with the electron beam EBmn so that the dose amount becomes the target amount Tx. At this time, if the rising time of the blanking signal output to the blanker BKmn is long, the time until the electron beam EBmn is blanked becomes long. Therefore, if the electron beam EBmn is shot multiple times on the sample 120 to draw a mark, the dose becomes larger than the target amount Tx, and the mark to be drawn becomes large.

  On the other hand, when the falling time of the blanking signal output to the blanker BKmn is long, the time until the irradiation of the sample 120 with the electron beam EBmn starts is long. Therefore, if the electron beam EBmn is shot a plurality of times on the sample 120 to draw a mark, the dose becomes smaller than the target amount Tx, and the mark to be drawn becomes smaller.

  As described above, when the delay time Ts at the start of irradiation and the delay time Te at the end of irradiation of the electron beam EBmn are large, the dose per shot increases or decreases. As a result, the size of the mark to be drawn also changes.

  FIG. 27 is a diagram showing the mark M drawn on the sample 120. A mark M indicated by a solid line indicates a mark drawn by one shot of the electron beam EBmn. For the mark M drawn in one shot, the ratio of the delay times Ts and Te to the irradiation time is small, so that the dose amount of the mark M is close to the target amount Tx.

  On the other hand, in a mark drawn by a plurality of shots, the ratio of the delay times Ts and Te to the irradiation time increases. For example, when the delay time Ts is longer and dominant than the delay time Te, a mark having a smaller area than the mark M is drawn, such as a mark Ms indicated by a broken line in FIG. When the delay time Te is longer and dominant than the delay time Ts, a mark having a larger area than the mark M is drawn, such as a mark Me shown by a dashed line in FIG.

  The difference in the mark size due to the dose amount appears regardless of the mark size or shape. Further, the size of the mark drawn by the specific electron beam BEmn changes depending on the number of shots, but the center position is a fixed position regardless of the number of shots. Thus, the electron beam lithography apparatus 10 compares marks drawn with different numbers of shots, and uses the result to correct the dose. Hereinafter, the dose correction processing will be described.

  The flowchart of FIG. 28 shows a series of processes executed by the CPU 101a according to the program stored in the auxiliary storage unit 101c. The dose correction processing is performed according to the flowchart shown in FIG.

  First, the CPU 101a reads the evaluation data stored in the auxiliary storage unit 101c (Step S401). This evaluation data is data that defines the evaluation pattern P0 shown in the SEM image Ph0 shown in FIG.

  Next, the CPU 101a draws an evaluation pattern using the area A1 of the aperture 51 (step S402). To write an evaluation pattern using the region A1, for example, the electron beams EBmn other than the electron beams EBmn passing through the openings H11 to H14, H21 to H24, H31 to H34, and H41 to H44 are blanked. Then, the evaluation pattern P1 based on the evaluation data is drawn using the 16 electron beams EB11 to EB14, EB21 to EB24, EB31 to EB34, and EB41 to EB44.

  To write the evaluation pattern P1, as shown in FIG. 12, first, a mark group MG1 including 16 marks arranged in a matrix of 4 rows and 4 columns is drawn. Here, each mark is simultaneously drawn using 16 electron beams EB11 to EB14, EB21 to EB24, EB31 to EB34, EB41 to EB44. When writing marks, the electron beams EB11 to EB14, EB21 to EB24, EB31 to EB34, and EB41 to EB44 are intermittently incident on the sample 120, so that a plurality of shots are performed, and each mark is printed. draw. Here, for example, it is conceivable to draw a mark in four shots.

  As described above, the irradiation time of each electron beam EBmn incident on the sample 120 when drawing the mark Mmn is assumed to be a constant value Td0. Therefore, when a mark is drawn by N shots using the electron beam EBmn, the irradiation time for one shot is Td0 / N. Specifically, when a mark is drawn in four shots, the irradiation time per shot is Td0 / 4.

  In a similar manner, as shown in FIG. 13, the mark group MG2 is drawn on the + Y side of the mark group MG1, and as shown in FIG. 14, the mark group MG3 is drawn on the -X side of the mark group MG1. Then, as shown in FIG. 15, the mark group MG4 is drawn on the −X side of the mark group MG2.

  FIG. 29 is a diagram illustrating an SEM image Phd1 of the evaluation pattern P1. As shown in FIG. 29, by drawing the mark groups MG1 to MG4 as described above, the evaluation pattern P1 including the mark groups MG1 to MG4 is drawn. In the evaluation pattern P1, each of the mark groups MG1 to MG4 includes 16 marks M11 to M14, M21 to M24, M31 to M34, and 16 marks drawn by the electron beams EB11 to EB14, EB21 to EB24, EB31 to EB34, and EB41 to EB44. M41 to M44.

  In the example shown in FIG. 29, the size of the marks M21 and M24 drawn by the electron beams EB21 and EB24 differs from the original size due to an error in the dose. Specifically, the mark size of the electron beam EB21 is larger than it should be when the irradiation time exceeds Td0. As for the electron beam EB24, the irradiation time is shorter than Td0, so that the size of the mark is smaller than it should be.

  Next, the CPU 101a draws an evaluation pattern using the area A2 of the aperture 51 (step S403). To write an evaluation pattern using the area A2, for example, the electron beams EBmn other than the electron beams EBmn passing through the openings H51 to H54, H61 to H64, H71 to H74, and H81 to H84 are blanked. Then, similarly to the drawing of the evaluation pattern P1, the evaluation pattern P2 based on the evaluation data is drawn using the 16 electron beams EB51 to EB54, EB61 to EB64, EB71 to EB74, and EB81 to EB84. When writing the evaluation pattern P2, the electron beams EB51 to EB54, EB61 to EB64, EB71 to EB74, and EB81 to EB84 are intermittently incident on the sample 120 to perform a plurality of shots. The pattern P2 is drawn.

  FIG. 30 is a diagram illustrating an SEM image Phd2 of the evaluation pattern P2. As shown in FIG. 30, by drawing the mark groups MG1 to MG4 in the manner described above, the evaluation pattern P2 including the mark groups MG1 to MG4 is drawn. In the evaluation pattern P2, each of the mark groups MG1 to MG4 includes 16 marks M51 to M54, M61 to M64, M71 to M74, and 16 marks drawn by the electron beams EB51 to EB54, EB61 to EB64, EB71 to EB74, EB81 to EB84. M81 to M84.

  In the example shown in FIG. 30, the size of the marks M62, M74, and M83 drawn by the electron beams EB62, EB74, and EB83 differs from the original size due to an error in the dose. Specifically, as for the electron beams EB62 and EB83, the irradiation time exceeds Td0, so that the mark size becomes larger than it should be. As for the electron beam EB74, the mark size becomes smaller than it should be due to the irradiation time being shorter than Td0.

  Next, the CPU 101a draws an evaluation pattern using the area A3 of the aperture 51 (step S404). To write an evaluation pattern using the region A3, for example, the electron beams EBmn other than the electron beams EBmn passing through the openings H15 to H18, H25 to H28, H35 to H38, and H45 to H48 are blanked. Then, similarly to the drawing of the evaluation patterns P1 and P2, the evaluation pattern P3 based on the evaluation data is drawn using the 16 electron beams EB15 to EB18, EB25 to EB28, EB35 to EB38, and EB45 to EB48. Also, when writing the evaluation pattern P3, the electron beams EB15 to EB18, EB25 to EB28, EB35 to EB38, and EB45 to EB48 are intermittently incident on the sample 120, so that a plurality of shots are performed. The pattern P3 is drawn.

  FIG. 31 is a diagram illustrating an SEM image Phd3 of the evaluation pattern P3. As shown in FIG. 30, by drawing the mark groups MG1 to MG4 in the manner described above, the evaluation pattern P3 including the mark groups MG1 to MG4 is drawn. In the evaluation pattern P3, each of the mark groups MG1 to MG4 has 16 marks M15 to M18, M25 to M28, M35 to M38 drawn by the electron beams EB15 to EB18, EB25 to EB28, EB35 to EB38, and EB45 to EB48. M45-M48.

  In the example shown in FIG. 31, the size of the marks M36 and M38 drawn by the electron beams EB36 and EB38 differs from the original size due to an error in the dose. Specifically, the mark size of the electron beam EB36 is larger than it should be when the irradiation time exceeds Td0. As for the electron beam EB38, the irradiation time is shorter than Td0, so that the mark size is smaller than it should be.

  Next, the CPU 101a draws an evaluation pattern using the area A4 of the aperture 51 (step S405). To write an evaluation pattern using the region A4, for example, the electron beams EBmn other than the electron beams EBmn passing through the openings H55 to H58, H65 to H68, H75 to H78, and H85 to H88 are blanked. Then, similarly to the drawing of the evaluation patterns P1 to P3, the evaluation pattern P4 based on the evaluation data is drawn using the 16 electron beams EB55 to EB58, EB65 to EB68, EB75 to EB78, and EB85 to EB88. When writing the evaluation pattern P4, a plurality of shots are performed by intermittently making the electron beams EB55 to EB58, EB65 to EB68, EB75 to EB78, and EB85 to EB88 impinge on the sample 120. The pattern P4 is drawn.

  FIG. 32 is a diagram illustrating an SEM image Phd4 of the evaluation pattern P4. As shown in FIG. 32, by drawing the mark groups MG1 to MG4 in the manner described above, the evaluation pattern P4 including the mark groups MG1 to MG4 is drawn. In the evaluation pattern P4, each of the mark groups MG1 to MG4 has 16 marks M55 to M58, M65 to M68, M75 to M78, and 16 marks drawn by the electron beams EB55 to EB58, EB65 to EB68, EB75 to EB78, EB85 to EB88. M85-M88.

  In the example shown in FIG. 32, there is no mark whose size differs from the original size due to an error in the dose.

  When the processes in steps S402 to S405 are performed, the evaluation patterns P1 to P4 are drawn on the sample 120 by a plurality of shots of the electron beam EBmn. The evaluation patterns P1 to P4 drawn on the sample 120 are imaged using a device such as an SEM, and stored in the auxiliary storage unit 101c of the control device 101 as SEM images Phd1 to Phd4.

  Next, the CPU 101a reads the SEM image Ph1 of FIG. 16 and the SEM image Phd1 of FIG. 29 stored in the auxiliary storage unit 101c. Then, the SEM image Ph1 and the SEM image Phd1 are compared to generate a difference image Dfd1 (step S406).

  In the comparison between the SEM images, the CPU 101a first matches the SEM image Ph1 with the SEM image Phd1. The SEM image matching calculates the normalized cross-correlation of the SEM image Phd1 while relatively moving the SEM image Phd1 with respect to the SEM image Ph1. Then, based on the calculation result, the SEM image Ph1 and the SEM image Phd1 are superimposed. In this state, the 64 marks of the SEM image Ph1 and the 64 marks of the SEM image Phd1 are accurately overlapped. Next, the CPU 101a generates a difference image Dfd1 between the SEM image Ph1 and the SEM image Phd1. Note that the SEM image is a black and white image, but the difference image Dfd1 may be binarized as necessary.

  FIG. 33 is a diagram illustrating the difference image Dfd1. As described above, the sizes of the marks M21 and M24 of the SEM image Phd1 are different from the sizes of the marks M21 and M24 drawn by one shot of the electron beams EB21 and EB24 due to a dose error. As described above, when the image size of the mark Mmn of the SEM image Ph1 is different from the image size of the mark Mmn of the SEM image Phd1, the difference image Dfd1 indicates a difference between the marks Mmn. The image in which the mark MM has appeared. Here, the mark MM21 for the mark M21 and the mark MM24 for the mark M24 appear in the difference image Dfd1.

  Next, the CPU 101a reads the SEM image Ph2 of FIG. 17 and Phd2 of FIG. 30 stored in the auxiliary storage unit 101c. Then, the SEM image Ph2 and the SEM image Phd2 are compared to generate a difference image Dfd2 (step S407).

  FIG. 34 is a diagram illustrating the difference image Dfd2. As described above, the sizes of the marks M62, M74, and M83 of the SEM image Phd2 are different from the sizes of the marks M62, M74, and M83 drawn by one shot of the electron beams EB62, EB74, and EB83 due to a dose error. In this case, a mark MM62 for the mark M62, a mark MM74 for the mark M74, and a mark MM83 for the mark M83 appear in the difference image Dfd2.

  Next, the CPU 101a reads the SEM image Ph3 of FIG. 18 and the SEM image Phd3 of FIG. 31 stored in the auxiliary storage unit 101c. Then, the SEM image Ph3 and the SEM image Phd3 are compared to generate a difference image Dfd3 (Step S408).

  FIG. 35 is a diagram illustrating the difference image Dfd3. As described above, the sizes of the marks M36 and M38 of the SEM image Phd3 are different from the sizes of the marks M36 and M38 drawn by one shot of the electron beams EB36 and EB38 due to a dose error. In this case, a mark MM36 for the mark M36 and a mark MM38 for the mark M38 appear in the difference image Dfd3.

  Next, the CPU 101a reads the SEM image Ph4 of FIG. 19 and the SEM image Phd4 of FIG. 32 stored in the auxiliary storage unit 101c. Then, the SEM image Ph4 and the SEM image Phd4 are compared to generate a difference image Dfd4 (step S409).

  FIG. 36 is a diagram illustrating the difference image Dfd4. As described above, the size of each mark in the SEM image Phd4 is equal to the size of a mark drawn in one shot. In this case, the mark MM does not appear in the difference image Dfd4.

  Next, the CPU 101a corrects the dose of the electron beam EBmn based on the difference images Dfd1 to Dfd4 (step S410).

  The correction of the dose is performed based on the area of the mark MM appearing in the difference images Dfd1 to Dfd4. Here, the area of the mark MMmn of the difference images Dfd1 to Dfd4 is Sdmn. The area Sdmn indicates the area of the mark of the SEM images Phd1 to Phd4 based on the marks of the SEM images Ph1 to Ph4. Therefore, when the marks of the SEM images Phd1 to Phd4 are larger than the marks of the SEM images Ph1 to Ph4, the area Sd has a positive value. Conversely, when the marks of the SEM images Phd1 to Phd4 are smaller than the marks of the SEM images Ph1 to Ph4, the area Sd has a negative value.

  The error Dsmn of the irradiation time per shot of the electron beam EBmn can be expressed as a function G (Sdmn) using the area Sdmn as a variable. Therefore, the CPU 101a calculates an error Dsmn for each electron beam EBmn based on the following equation (1).

Dsmn = G (Sdmn) (1)

  After calculating the error Dsmn, the CPU 101a corrects the irradiation time Tbmn of the electron beam EBmn based on the following equation (2), and calculates a new irradiation time Tamn.

Tamn = Tbmn + Dsmn (2)

  For example, as described in the first embodiment, when the irradiation times Td1 (i) to Td4 (i) are calculated, the irradiation times Td1 (i) to Td4 (i) are corrected by the following equation. , New irradiation times TAd1 (i) to TAd4 (i) are calculated.

TAd1 (i) = Td (i) + Dsmn
TAd2 (i) = Td (i) + Dsmn
TAd3 (i) = Td (i) + Dsmn
TAd4 (i) = Td (i) + Dsmn

  After calculating the corrected irradiation times TAd1 (i) to TAd4 (i) for each of the 64 electron beams EBmn, the CPU 101a stores the irradiation times TAd1 (i) to TAd4 (i) in the auxiliary storage unit, The correction processing ends.

  The electron beam lithography apparatus 10 irradiates an electron beam EBmn based on the calculated irradiation times TAd1 (i) to TAd4 (i) when drawing a pattern. Thereby, the error of the dose per shot is corrected for each electron beam EBmn, and the electron beam EBmn can be incident on the sample 120 so as to have a dose based on the design value.

  As described above, in the present embodiment, the error of the dose amount per shot is corrected for each electron beam EBmn (step S410). Therefore, there is no difference in the dose per shot between the electron beams EBmn, and as a result, a pattern can be accurately drawn on a sample using a plurality of electron beams EBmn.

  In the present embodiment, the variation of the dose due to the variation of the area of the opening Hmn provided in the aperture 51 is adjusted by the correction processing (Steps S301 to S312). Then, the error of the dose amount due to the shot operation of the electron beam EBmn is corrected. Therefore, it is possible to draw a pattern on a sample with a target dose.

  In a multi-beam type electron beam lithography apparatus, a pattern is generally drawn using 1,000 or more electron beams. Therefore, the aperture 51 for multiplying the electron beam from the electron gun 30 is actually provided with a large number of openings. Therefore, it has been conventionally difficult to evaluate the variation in the area of the opening of the aperture 51. Also, regarding the dose amount of each electron beam, an error has occurred with respect to the target amount due to the delay of the rise and fall of the blanking signal. It is relatively difficult to separate a dose error caused by a blanking signal or the like from a dose error caused by variation in the area of the opening. However, by performing the dose correction processing according to the present embodiment, it is possible to accurately correct a dose error caused by a blanking signal or the like.

  Further, in the present embodiment, the error of the dose caused by the blanking signal or the like can be quantitatively obtained based on the area of the mark MM appearing in the difference image. Therefore, it is possible to correctly evaluate not only the error in the dose amount but also the variation in the area of the opening of the aperture 51.

  In the present embodiment, the marks M forming the evaluation patterns P1 to P4 are drawn by four shots as an example. However, the present invention is not limited to this. For example, the mark M may be drawn by two or three shots of an electron beam, or may be drawn by five or more shots of an electron beam.

  In the dose correction processing according to the present embodiment, a dose error can be calculated from a difference image obtained by comparing SEM images representing the evaluation patterns P1 to P4 drawn with different numbers of shots. In the present embodiment, difference images Dfd1 to Dfd4 obtained from SEM images Ph1 to Ph4 having marks M drawn in one shot and SEM images Phd1 to Phd4 having marks M drawn in N shots are obtained. And the dose was evaluated. However, the present invention is not limited thereto. For example, difference images obtained from SEM images Ph1 to Ph4 having marks M drawn by M shots having different numbers of times and SEM images Phd1 to Phd4 having marks M drawn by N shots The dose may be evaluated using Dfd1 to Dfd4. Note that M ≠ N.

  The embodiments of the present invention have been described above, but the present invention is not limited to the embodiments. For example, in the above-described embodiment, each area A1 to A4 of the aperture 51 is evaluated using the difference images generated based on the SEM images Ph1 to Ph4. The comparison between the SEM images Ph1 to Ph4 is not limited to this. For example, the respective areas A1 to A4 of the aperture 51 may be evaluated by comparing the average brightness of each area of the SEM image.

  In the above-described embodiment, the case where the aperture 51 is divided into four regions A1 to A4 as illustrated in FIG. 11 has been described. The invention is not limited thereto, and the aperture 51 may be divided into five or more regions.

  The above embodiment has described the case where the aperture 51 is evaluated using the evaluation pattern P0 drawn by all the electron beams EBmn. However, the present invention is not limited to this. For example, the evaluation pattern P0 drawn by all the electron beams EBmn may be drawn by using a part of the electron beams. In this case, for example, the evaluation pattern P0 may be drawn using the electron beams EB1m, EB3m, EB5m, and EB7m, or drawn using the electron beams EBn1, EBn3, EBn5, and EBn7.

  In the above-described embodiment, the case where 64 apertures Hmn are formed in the aperture 51 has been described. The invention is not limited thereto, and the aperture 51 may have an opening of 63 or less, or may have an opening of 65 or more.

  In the above embodiment, the control device 101 of the electron beam drawing apparatus 10 executes the evaluation processing and the correction processing. However, the present invention is not limited to this, and the evaluation processing or the correction processing may be executed by an inspection device different from the electron beam drawing device 10 or a computer.

  In the above embodiment, the case where the evaluation processing or the like is performed using the SEM images Ph0 to Ph4 of the evaluation pattern has been described. Without being limited to this, when the inspection apparatus or the electron beam lithography apparatus 10 has a function for observing the evaluation pattern, instead of the SEM image, using the image captured by the above-described apparatus or the like, Evaluation processing or the like may be performed.

  The functions of the control device 101 according to each of the above embodiments can be realized by dedicated hardware or by a normal computer system. The program stored in the auxiliary storage unit 101c of the control device 101 is stored in a computer-readable recording medium such as a flexible disk, a CD-ROM (Compact Disk Read-Only Memory), and a DVD (Digital Versatile Disk). It may be distributed by. Also, the program may be stored in the auxiliary storage unit 101c by installing the program on a computer via the Internet.

  All or a part of the above-described program is executed on, for example, a server, and the control device 101 that has received the information on the execution result via the communication network may execute the above-described processing (steps S101 to S410). .

  Although several embodiments of the present invention have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These new embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and their equivalents.

DESCRIPTION OF SYMBOLS 10 Electron beam drawing apparatus 20 Irradiation apparatus 30 Electron gun 41-43 Lens 51, 52 Aperture 61 Blanking unit 62 Deflector 70 Stage 80 Vacuum chamber 80a Lighting chamber 80b Lens barrel 100 Control system 101 Control device 101a CPU
101b Main storage unit 101c Auxiliary storage unit 101d Input unit 101e Display unit 101f Interface unit 101g System bus 102 Power supply unit 103 Lens drive unit 104 Blanking amplifier 105 Deflection amplifier 106 Stage drive unit 120 Sample 610 Substrate 611, 612 Electrodes A1 to A4 AA1 to AA4 area BKmn blanker Df1 to Df4, Dfd1 to Dfd4 Difference image EBmn Electron beam Hmn Opening HHmn Opening Mmn mark Mx, My mirror MG1 to MG4 Mark group P0 to P4 Evaluation pattern Ph0 to Ph4, Phd1 to Phd4

Claims (10)

An evaluation method for evaluating the accuracy of an aperture in which a plurality of openings are formed,
Drawing a first evaluation pattern based on the evaluation data using a plurality of electron beams generated by passing an electron beam through the aperture;
Dividing the aperture into a plurality of regions including the plurality of openings, and defining a plurality of divided regions;
Using an electron beam passing through any one of the plurality of divided regions, based on the evaluation data, drawing a second evaluation pattern different from the first evaluation pattern;
Comparing the first evaluation pattern and the second evaluation pattern;
Evaluating the accuracy of the aperture based on a comparison result between the first evaluation pattern and the second evaluation pattern;
Evaluation method including:   The evaluation method according to claim 1, wherein, in the step of drawing the second evaluation pattern, the second evaluation pattern is drawn for each of the divided areas. The evaluation pattern includes a unit mark drawn by each of the electron beams,
In the step of comparing the first evaluation pattern and the second evaluation pattern,
The evaluation method according to claim 1, wherein the size of the mark of the first evaluation pattern is compared with the size of a mark of the second evaluation pattern corresponding to the mark of the first evaluation pattern. A correction method for correcting the dose of each of a plurality of electron beams passing through an aperture formed with a plurality of openings,
Dividing the aperture into a plurality of regions including the plurality of openings, and defining a plurality of divided regions;
Drawing a first evaluation pattern including a mark corresponding to each electron beam using a plurality of electron beams generated by passing through the first divided region based on the evaluation data;
Obtaining a first correction value based on a difference in size of each of the marks included in the first evaluation pattern with respect to a preset reference pattern;
Drawing a second evaluation pattern including a mark corresponding to each electron beam using a plurality of electron beams generated by passing through a second divided region different from the first divided region based on the evaluation data The process of
Comparing the first evaluation pattern and the second evaluation pattern, and based on a difference between the size of the mark of the first evaluation pattern and the mark of the second evaluation pattern corresponding to the mark of the first evaluation pattern. Obtaining a second correction value;
A dose of the electron beam that has passed through the first divided area is corrected based on the first correction value, and the electron beam passes through the second divided area based on a sum of the first correction value and the second correction value. Correcting the dose of the electron beam,
Correction method including: A correction method for correcting the dose of each of a plurality of electron beams passing through an aperture formed with a plurality of openings,
Performing the evaluation method according to claim 3;
Obtaining a first correction value based on a difference between the size of each of the marks included in the second evaluation pattern with respect to a mark of a preset reference pattern;
Obtaining a second correction value based on a difference between the size of the mark included in the second evaluation pattern and the mark size of the first evaluation pattern, based on an evaluation result of the evaluation method;
The dose of the electron beam that has passed through the first divided area is corrected based on the first correction value, and the dose other than the first divided area is corrected based on the sum of the first correction value and the second correction value. Correcting the dose of the electron beam passing through the divided region,
Correction method including: A first pattern formed by shots of the electron beam for a first number of times based on the evaluation data, and a second number of shots different from the first number of shots of the electron beam based on the evaluation data A comparing step of comparing the second pattern formed by
A correcting step of correcting a dose amount of the electron beam based on a comparison result between the first pattern and the second pattern;
Correction method including: In the comparing step, a difference image is generated between a first image indicating the first pattern and a second image indicating the second pattern,
The correction method according to claim 6, wherein in the correction step, the dose of the electron beam is corrected based on an area of a region indicating a difference between the first pattern and the second pattern of the difference image.   The correction method according to claim 6, wherein the first number is one. In a control device of an electron beam lithography apparatus having an aperture in which a plurality of openings are formed,
Drawing a first evaluation pattern based on the evaluation data using a plurality of electron beams generated by passing the electron beam through the aperture;
Dividing the aperture into a plurality of regions including the plurality of openings, and defining a plurality of divided regions;
A step of drawing a second evaluation pattern different from the first evaluation pattern based on the evaluation data, using an electron beam passing through any one of the first divided areas of the plurality of divided areas;
Comparing the first evaluation pattern and the second evaluation pattern,
A step of evaluating the accuracy of the aperture based on a comparison result between the first evaluation pattern and the second evaluation pattern;
A program for executing An electron beam lithography apparatus having an aperture in which a plurality of openings are formed, and drawing a pattern on a sample,
Drawing a first evaluation pattern based on the evaluation data using a plurality of electron beams generated by passing the electron beam through the aperture;
Dividing the aperture into a plurality of regions including the plurality of openings, and defining a plurality of divided regions;
A step of drawing a second evaluation pattern different from the first evaluation pattern based on the evaluation data, using an electron beam passing through any one of the first divided areas of the plurality of divided areas;
Comparing the first evaluation pattern and the second evaluation pattern,
A step of evaluating the accuracy of the aperture based on a comparison result between the first evaluation pattern and the second evaluation pattern;
A storage device for storing a program for performing
A control device that executes the program stored in the storage device;
An electron beam lithography apparatus having:

Images